It has been known for some time that produce stored under refrigeration maintains its freshness for a longer period of time than produce stored at ambient temperatures. For example, the refrigerated shipments of produce from California to the East Coast has been done since the 1920's. It is not as widely known, but is familiar to those in the business, that controlling the composition of the atmosphere in the area where storage is being undertaken extends the lifetime of food products.
An apparatus for producing a controlled atmosphere is described in U.S. Pat. No. 4,817,391 issued Apr. 4, 1989 to applicant.
Controlled atmosphere storage is usable for a wide variety of food products. For the purpose of this application, food products are defined to include all materials of plant or animal origin intended for the consumption of man or animals. By way of non-limiting limiting example, such products include fruit, vegetables, produce, meats, dairy products, grains, and seafood products.
Such storage can be accomplished either at a warehouse or during the transport of the food products. A desireable apparatus would be usable in warehouses, ships, train cars, trucks, and containers for shipment in any of the above modes of transportation.
The apparatus should be able to be conformed to produce any desired combination of atmospheric gases. The selection should be adjustable to alter the atmospheric composition for a particular product. For example, the concentration of ethylene is critical for storage of fruits, but relatively unimportant for storage of meats.
The method and apparatus illustrated in applicants earlier patent described above accomplishes the above goals. Capacity of the above apparatus is limited, however, by the size of the area in which the controlled atmosphere is sought. Attempts to increase capacity by merely scaling up the apparatus have not been totally successful. In addition, the use of the above apparatus puts a lower limit on the amount of oxygen that can be removed from the system. Accordingly, there is a need for a high capacity apparatus that can produce any desired atmosphere.